Digital designs can be made into physical objects by 3D printing, which is also known as additive manufacturing. 3D printing typically comprises depositing or fusing materials in a layer-by-layer manner to create cross-sections of the 3D printed object. Because deposited or fused material may undergo stresses as the material changes temperature, chemical composition, crystal structure, or the like, 3D printed objects can warp during the 3D printing process, and there are prior art techniques for controlling the respective processes to compensate for stresses to eliminate or minimize undesirable warping.
For example, one 3D printing technique commonly referred to as fused deposition modeling can create warping in the first few layers of the 3D printed object based upon the internal stresses causing the initially deposited material to curl up and separate from the print plate upon which the 3D printed object is 3D printed. An example of such curl and separation is shown in the bottom features of the 3D printed object shown in FIG. 1.
Prior art techniques for eliminating or minimizing such curl and separation include printing a raft under the 3D printed object which serves as a transition between the print plate and the 3D printed object. However, such rafts are difficult to remove from the 3D printed object, particularly if the raft and 3D printed object are made from the same build material, and rafts typically leave undesirable defects on the surfaces of the 3D printed object that contacted the raft, and those features must be cut, sanded off, or otherwise removed or hidden.
A further prior art technique is printing anchors at the locations of the 3D printed object most likely to curl or warp based upon the geometry of the 3D printed object. Anchors are typically only one, two, or a few layers thick and increase the surface area of contact between the 3D printed material and the print plate to prevent the 3D printed object from curling and separating from the print plate. FIGS. 2 and 3 show a prior art technique of adding a circular anchor to the corner of a 3D printed object.
One disadvantage of using anchors is they may be difficult to remove and can leave defects on the surface of the 3D printed object from which it is removed.
Yet another prior art technique for preventing curl or warp is the 3D printing of a brim (also known as a skirt) around the entire perimeter of the 3D printed object. A brim is similar to anchors but instead of being positioned only at certain portions of the 3D printed object, the brim simply encircles the entire 3D printed object. Users of the 3D printer can set how wide and thick the brim will be. FIG. 4 shows two 3D printed objects encircled by a brim on the bottom layer(s).
Similar to anchors, brims can be difficult to remove and can leave defects on the surface of the 3D printed object caused by the removal of the brim from the 3D printed object. For example, sometimes knives, box cutters, or other handtools may be required to remove an anchor or brim, which can be dangerous for the user and can leave flaws or other defects on the surface of the 3D printed object.
Therefore a need exists for methods and devices for preventing curl and warping of 3D printed objects without creating difficulty to remove the device from the object and without leaving defects on the 3D printed object.